Aside from car and truck sales, online music sites are making big inroads through the explosion in mobile devices. "If you look at Pandora alone, they've got 65 million in registered listeners in the US. They got 19 million of them on iPhone apps alone, which is equal to the number of subscribers that Sirius has," Cox said.

Sirius vs. Pandora

Could Pandora open a can of worms for Sirius XM? Rob Cox, of Reuters Breakingviews, and "The Strategy Session" hosts discuss.

"They also have this huge change in technology, which is really going to change everything. You can access these guys in your car, which is where half of all radio listening takes place. So you have to look in your rear view mirror a little bit and ask yourself whether or not there is going to be a real challenge to Sirius' dominance," he said.

"For now I think Sirius has got something that no one else has, it's got an incredible content—over 130 stations. The issue is how much you are actually paying for stuff that isn't music. But I think they are in a good situation," Cox said.

"I wouldn't be surprised if in the next year or two Pandora tries to get into this business," Cox concluded.